Need a word for "something that requires many tries and attempts."

Question

I'm working on this English homework where I have to translate a text from my native language into English. There's one word that means "something that requires numerous attempts" or "something that requires retrying." I cannot say "trial and error" because the original text didn't really mention anything about errors. It is basically a sentence literally translated into something like " X requires retrying.". So my question is, is there a word to describe that? For example,

X is ___.

or

X requires ___ [something better than retrying].

Answer 1

X requires persistence

persistence noun.
1. the quality of persisting; tenacity.
2. the act of persisting; continued effort or existence.
— Collins

Answer 2

Seems like you need perseverance.

[MASS NOUN] Persistence in doing something despite difficulty or delay in achieving success.
‘medicine is a field which requires dedication and perseverance’

Reference:
https://en.oxforddictionaries.com/definition/perseverance

Answer 3

Iterations

noun
The repetition of a process or utterance.
oxford

Iterations implies one builds on the next. Not sure if that is the case here or not.

Answer 4

What about "X requires many attempts"? Alternately, you could phrase the issue in terms of success being a low probability proposition. Perhaps "X is unlikely to occur in any one attempt".

Answer 5

Do you think that error always means mistake and that is why you think you can't use trial and error?

Error certainly can mean avoidable mistake but if you look at definition 1.2 of this dictionary entry you will see that error can also mean unavoidable inaccuracy, such as the inaccuracy introduced into money calculations when applying percentages.

This definition of trial and error shows that, here, error is used more in the sense of unavoidable inaccuracy than in the sense of making mistakes. All the experimental attempts at a solution are usually valid attempts given the experimenter's level of knowledge, and the seriousness of the failures is reduced over the repetitions of the trial because the experimenter is learning from experience.

In fact electronic calculators often use a form of rapid trial and error to arrive at mathematical results like sines, cosines and logarithms by calculating closer and closer estimates for the value until a sufficiently accurate one is achieved.

Properly understood trial and error is probably your best coice.

Answer 6

Perhaps, it is elusive (and hence requires multiple attempts).

X is elusive.

ODO:

elusive ADJECTIVE

1 Difficult to find, catch, or achieve.

‘success will become ever more elusive’

‘Taylor is still searching for that elusive first tour win but is not setting herself any future goals and targets in the sport.’

‘Naturally, that persistent little squirrel is still driving himself nuts in pursuit of an elusive acorn.’

Answer 7

Well you can use hard-to-gain to state that.

Like this: "X is extremely hard-to-gain."

or with requires you may use an iron shoe to accomplish, means very hard work to do.

Which will lead to: "X requires an iron shoe to accomplish".

Hope it helps.